The invention is directed to an elevator system for the vertical transport of loads in an aircraft, particularly for the transport of trolleys between the different decks of an airplane.
Elevator systems in aircraft are subject to special requirements with respect to stability, reliability of operation and load retention because of special dynamic stresses during flight (different force effects at take-off and landing or during turbulence). For this reason, certain known elevator principles, e.g., drive sheave with hoist rope and load counterweights, and rope drum wind-up, are ruled out from the outset.
As regards gravitational force and acceleration forces, independent drives are known in different constructions. Among these latter are, for example, hydraulic drives in which the elevator cabin is moved vertically above a hydraulic cylinder comprising multiple members. The heavy weight and substantial space requirement below the elevator cabin are disadvantageous and unacceptable for aircraft.
Further, rack-and-pinion drives have been used as elevator drives. In this type of drive, it is disadvantageous that the drive motor travels along with the cabin as an additional load and that an upward movement and downward movement which is free from play requires extensive adjustment and maintenance.
Spindle drives have been most successful in aircraft because the elevator drive which is free from play can be constructed in a substantially improved manner. In this drive, a vertically arranged spindle is driven in a column, this spindle providing for the upward movement and downward movement and vertical fixing of the cabin by means of a spindle nut communicating with the elevator cabin. The column itself has suitable open strand sections at which the cabin is guided. However, there remain the disadvantages of high maintenance due to lubrication, a relatively substantial noise level and relatively heavy weight of the load-carrying spindle and its bearing.
The invention teaches a novel possibility for the arrangement of an elevator system for the vertical transport of loads in an aircraft which permits low-noise, reliably operating conveying between different levels of the aircraft and reliable stopping in the loading and unloading positions and which is characterized by low maintenance and low weight. Elevator system for the vertical transport of loads in an aircraft containing an elevator cabin (2), and a mast (1) for carrying and guiding the elevator cabin (2) between different horizontal levels, wherein the elevator cabin is moved and locked in a defined manner by a drive system arranged at the mast, characterized in that the mast (1) has a load-bearing, slender construction of hollow sections (11) and guide rails (13) and a lower mast fastening and upper mast fastening such that the lower mast fastening (15) is mounted so as to move in pendulum fashion around a vertical axis of the aircraft (5) for deliberately transferring all weight forces of the mast (1) to a supporting structure (51) of the aircraft (5), and for receiving all horizontal forces the upper mast fastening (16) connects the mast (1) in longitudinal and transverse axis of the aircraft (5) to a supporting structure (52) of the aircraft (5) located higher such that the mast (1) does not offer any resistance to the movements of the higher supporting structure (52) relative to the lower mast fastening (15), in that a drive system (4) with a drive motor (41) having a high torque and good controllability has at least one closed belt (46) for transferring the torque from the drive motor to the elevator cabin and for transferring load from the elevator cabin (2) to the mast (1), wherein the belt (46) is guided and pretensioned in a defined manner at the lower end and upper end of the mast (1) via a drive roll and a deflection roll (44; 45) and has a toothing adapted to the drive roll and deflection roll (44, 45) and, between the drive roll and deflection roll (44; 45), at least one freely accessible belt portion oriented parallel to the mast (1) for fastening the elevator cabin (2) and its movement along the mast (1).
In an elevator system for the vertical transport of loads in an aircraft containing an elevator cabin and a mast for load carrying and for guiding the elevator cabin between different horizontal levels, the above-stated object is met, according to the invention, in that the mast (1) has a load-bearing, slender construction of hollow sections (11) and guide rails (13) and has a lower mast fastening and upper mast fastening such that the lower mast fastening (15) is mounted so as to move in pendulum fashion around a vertical axis of the aircraft (5) for deliberately transferring all weight forces of the mast (1) to a carrying base structure (51) of the aircraft (5), and for receiving all horizontal forces the upper mast fastening (16) connects the mast (1) in longitudinal and transverse axis of the aircraft (5) to a supporting structure (52) of the aircraft (5) located higher such that the mast (1) does not offer any resistance to the movements of the higher supporting structure (52) relative to the lower mast fastening (15), and in that the drive system has a drive motor (41) having a high torque and good controllability and at least one closed belt for transferring the torque to the elevator cabin and for transferring load from the elevator cabin to the mast, wherein the belt is guided and pretensioned in a defined manner at the lower end and upper end of the mast via a drive roll and a deflection roll (44; 45), a toothing adapted to the drive roll and deflection roll (44, 45) and, between the drive roll and deflection roll, at least one freely accessible belt portion oriented parallel to the mast for fastening the elevator cabin and its movement along the mast.
The toothing of the belt and drive roll and deflection roll advantageously has an additional lateral guide in order to prevent the belt from wandering out of the running surface of the driving and deflection rolls. The belt and the driving and deflection rolls preferably have a spiral toothing or spur toothing with a circulating splined guide.
The belt is advisably formed of a base material of ductile plastic and longitudinally oriented strand inlays. The base material of the belt preferably comprises polyurethane in which steel wires or carbon fibers (carbon strands) are inserted.
The toothing of the belt advantageously has a more wear-resistant layer, preferably polyamide, over the base material at the tooth flanks in order to reduce belt wear.
In order to increase reliability and safety, it has proven advantageous when a plurality of belts are provided as load carrying means for the elevator cabin, wherein the deflection rolls of the belts which are guided next to one another are arranged on a separate shaft at the upper end of the mast and the drive rolls are arranged on a common drive shaft at the lower end of the mast.
A belt monitoring device for monitoring belt tension and detecting belt damage is advisably provided at the upper end of the mast, wherein tearing or a loss in width during load transport causes the drive motor to be shut off and the belt pretensioning can be checked and adjusted during idling.
Vertical oscillations of the elevator cabin are extensively suppressed in that a tensioning device is advantageously provided for the belts and is arranged in an area of the freely accessible belt portion that is concealed by the elevator cabin, so that the belt can be readjusted by applying defined pretensioning.
To simplify the control of the elevator cabin and motor, the drive motor advisably has a measuring device for detecting rotor positions, so that the position of the elevator cabin can be correlated to the rotor position of the drive motor by means of this measuring device via the toothing of the belts. The position of the elevator cabin relative to the floor of a respective deck of the aircraft is accordingly adjustable in a continuous and simple manner preferably by programming a controlling and regulating circuit which is arranged downstream of the measuring device for rotor position detection. For this purpose, the drive motor is advantageously guided at an AC converter which, based on the measurements of the rotor position, regulates the current of the drive motor, determines the exact position of the elevator cabin and moves toward a predetermined position in a deliberate manner.
Because of the requirements for high torque and very good controllability, a brushless DC servo motor which is temperature-monitored in addition for detecting interference and overload is advantageously used as drive motor.
A step-down gear unit is advantageously provided for generating or holding a high torque of the drive shaft required for driving and braking.
A mechanical brake device is advisably provided at the drive shaft to stop the elevator cabin in the currentless state of the drive motor in case of overload or breakdown.
The mast which has the function of supporting and guiding the entire elevator cabin is advantageously formed of hollow sections whose quantity and size are adapted to the quantity and dimensions of the belts. The hollow sections are constructed as channels for the return of the belts. The mast preferably has end modules at the end of the hollow sections for receiving the driving and deflection rolls.
In order that all of the weight forces can be deliberately received by the mast via the lower mast fastening in the supporting structure of the aircraft, the lower mast fastening is advantageously constructed in a lower deck of the aircraft as a pendulum bearing so as to ensure a movability of the mast in the longitudinal axis and transverse axis of the aircraft about this pendulum bearing. On the other hand, for receiving all horizontal forces at a higher deck of the aircraft, the mast is preferably fastened via a sliding pendulum bearing which fixes the mast in the longitudinal axis and transverse axis of the aircraft but does not offer resistance to the movements of the deck relative to one another. For this mast construction, it is advantageous that stiffening or reinforcement is provided only in the region of the lower pendulum bearing in the supporting structure of the aircraft for load suspension of the entire elevator system.
Further, at the sides, i.e., in transverse direction to the side on which the elevator cabin is arranged, the mast advantageously has a section rail or two U-sections located across from one another as guide rails for the movement of the elevator cabin.
For supporting the live load and inherent load of the elevator cabin in the orthogonal plane relative to the longitudinal direction of the mast, a plurality of groups of guide rollers are advantageously provided at the guide rails for guiding the elevator cabin along each side of the mast, which guide rollers roll on different surfaces of the respective guide rail of the mast closely adjacent to one another. The groups of guide rollers preferably contain pairs of rollers, at least two pairs rolling on different rolling surfaces on each guide rail.
The different rolling surfaces of the guide rails on which a pair of rollers rolls are advantageously the (almost concealed) inner sides of the U-section legs in a guide rail with U-section. In case of an individual rail (T-section), the guide rollers would roll in a functionally identical manner on opposite surfaces of one and the same shaped part of the rail.
The guide rollers of a group are advisably arranged at an offset to one another in direction of the guide rail in order to be accommodated in a space-saving manner in a U-shaped guide rail. Otherwise, the guide rollers must be arranged opposite one another orthogonally in pairs. In order to adjust the pairs of guide rollers without play relative to the rolling surfaces of the guide rail, it is advantageous when at least one guide roller of a pair is mounted on a shaft which can be adjusted eccentrically.
For exact guidance of the elevator cabins relative to the mast in each horizontal direction, the guide rollers are preferably constructed in a first variant as two-roller systems, wherein the latter have a non-rotating central part about which the main guide roller revolves and at which a smaller transverse guide roller is embedded on the front side with respect to the main guide roller in such a way that the two-roller system rolls in a defined manner at a side surface as well as at the base (U-section base or rail flange) of the guide rail.
However, in another design variant of the guide rollers, pairs of simple standard rollers can also be associated with the opposite running surfaces of the guide rail and there can be a third, separate transverse guide roller in the immediate vicinity of the pair of rollers.
A slide is advantageously provided between the mast and elevator cabin for coupling the elevator cabin to the freely accessible belt portion and for linear guidance along the mast. The guide rollers for guiding the elevator cabin which engage laterally in the mast are fastened to the slide and there is a mounting surface for the rigid fastening of the elevator cabin.
The slide advisably has the shape of a wide U-section. The mast essentially penetrates inside this U-shaped slide and the shafts of the guide rollers are oriented parallel to the mounting surface of the slide at the inner sides of the legs of the slide, and sections of the guide rails of the mast engage in the oppositely located sections.
The elevator cabin is preferably fastened to the slide by means of a quick-closure to facilitate maintenance and exchange. For this purpose, at least one pin is advisably provided at the slide for load suspension of the elevator cabin and to aid in assembly. The elevator cabin is fastened to the slide so as to be secured against slippage by means of a quarter-turn fastener or an eccentric lever or a screw connection between the elevator cabin and slide.
The fundamental idea of the invention is based on the thought that the particular conditions for elevator systems in air travel and space travel, namely, guaranteeing unconditional protection against negative accelerations and uncontrolled movements of the elevator cabin in all conceivable movement sequences of the aerodynamic vehicle while simultaneously limiting volume and weight and reducing maintenance and noise, can only be met by departing from gearing types comprising toothed metal linear drives. The solution consists in that the cabin movement is carried out by means of a conveying belt drive which satisfies the necessary conditions in cooperation with an anti-slip device (toothed belt) and determined measuring and regulating devices (belt monitoring device and measuring device for detecting the rotor position). In addition, a suitable column construction (mast supported on pendulum bearings) is provided for vertical load suspension, which column construction, in particular, meets the requirements of compatibility with respect to twisting or torsion and other positional deviations (caused, e.g., by temperature variations) of the supporting structure of an aerodynamic vehicle and, besides the supporting function, also takes over the linear guidance of the cabin slide and the lateral support of the elevator system. Due to the fact that this type of drive is not dependent on gravitational force and due to the load-independent slide guide and the sliding guidance of the mast (sliding/pendulum bearing), application of the invention is not limited to aircraft and should be expressly understood as extending also to space vehicles.
In an elevator system for aircraft which is realized in the manner mentioned above, a low-noise, reliably operating transport of loads between different levels (decks) of an aerodynamic vehicle and dependable stopping in the charging and unloading positions are achieved with reduced weight and reduced maintenance.